1. Field of the Invention
The present invention relates to an optical transmitting and receiving module holder and an optical module. In particular, the present invention relates to an optical transmitting and receiving module holder and an optical module thereof, in which the optical transmitting and receiving module holder uses an optical transmitting module holder section and an optical receiving module holder section in combination for optical fiber communication.
2. Description of the Related Art
In recent years, with the increasing speed and the increasing capacity of data communication, the demand for an optical fiber communication technology using optical fiber as an optical transmission line is rising. In such optical fiber communication, a transmitting end converts a signal to be transmitted to an electrical signal. Based on the electrical signal, the transmitting end transmits an optical signal formed from light emitted from a communication light source to a receiving end using an optical fiber. A light detector receives the transmitted optical signal. The optical signal is reverted to the electrical signal, and the electrical signal is converted to a required signal. In this way, an optical module is used to convert the optical signal led in by the optical fiber to the electrical signal, or to convert the electrical signal to the optical signal and lead out the optical signal to the optical fiber. The optical module used in optical fiber communication such as this includes a photoelectric conversion element package (for example, a package housing a semiconductor light emitting element or a semiconductor light receiving element), a ferrule, a lens, and a holder. The ferrule holds an end face of the optical fiber. The lens optically couples the photoelectric conversion element within the photoelectric conversion element package with the optical fiber held by the ferrule and enables optical communication. The holder houses the photoelectric conversion element package, the ferrule, and the lens.
As an optical module such as this, for example, various optical modules having the following configuration are known. An engaging section is formed on one end of a sleeve. A ferrule used to position an optical fiber is engaged with the engaging section. An element housing section is formed on the other end of the sleeve on a same axis as the engaging section. A lens holding section is formed between the engaging section and the element housing section. The element housing section houses the semiconductor light emitting element or light receiving element. The lens holding section holds a light-collecting lens. However, in these optical modules, the semiconductor light emitting element or the semiconductor light receiving element, the ferrule, and the lens are respectively individual components. Therefore, when these components are attached to the holder, a centering operation is required to be performed so that the optical axis of each component matches. The centering operation is difficult. As a result, there is a problem in that operation efficiency is poor.
To solve this problem, the present applicant has proposed optical modules in which a lens and a holder are integrally formed (for example, refer to Patent Literatures 1 to 3). In these optical modules, the position alignment of the optical axis of the lens and the axis line of the holder becomes unnecessary. Therefore, the assembly operation of the optical module is facilitated, and the manufacturing efficiency of the optical module can be enhanced.
A holder for an optical module such as this in which the lens is integrally formed can be used as an optical transmitting module holder section and an optical receiving module holder section of an optical light transmitting and receiving module of an optical transceiver. FIG. 10 is a typical example of an optical transmitting and receiving module such as this. As shown in FIG. 10, in an optical transmitting and receiving module 310, an optical module holder section 312 and an optical module holder section 314 respectively house a CAN-type package 316 and a CAN-type package 318. The CAN-type package 316 houses a laser diode (LD) as a light emitting element. The CAN-type package 318 houses a photo diode (PD) as a light receiving element.
Further popularization of fiber-to-the-home (FTTH), home networks, in-vehicle LAN, and the like is expected in the future. A reduction in the cost of the optical transceivers used in FTTH, home networks, in-vehicle LAN, and the like is imperative. Therefore, in place of the CAN-type package, a board-mounted-type package having low manufacturing cost is becoming popular. FIG. 11 is an example of an optical transmitting and receiving module using a board-mounted-type package such as this. As shown in FIG. 11, in an optical transmitting and receiving module 410, an optical module holder 412 and an optical module holder 414 are mounted on a board 416, on which a light emitting element and a light receiving element are mounted. In the optical transmitting and receiving module 410 using the board-mounted-type package, an alignment of the optical components in a Z direction (direction of the optical axis of the lens) is not required. Therefore, cost reduction due to a shortening of manufacturing time can be achieved. In addition, generally, as shown in FIG. 12A and FIG. 12B, a slight gap is provided between an optical transmitting module holder section 512 and an optical receiving module holder section 514 of an optical transmitting and receiving module holder 510. Respective alignments of the optical transmitting module and the optical receiving module are performed during the assembly between optical components. However, simultaneous alignment in a state in which the optical transmitting module holder section and the optical receiving module holder section are engaged is also proposed (for example, refer to Patent Literature 4).
Patent Literature 1: Japanese Patent Laid-open Publication No. 2004-239997 (Paragraph No. 0008)
Patent Literature 2: Japanese Patent Laid-open Publication No. 2004-294636 (Paragraph No. 0013)
Patent Literature 3: Japanese Patent Laid-open Publication No. 2004-354452 (Paragraph No. 0013 to 0030)
Patent Literature 4: U.S. Pat. No. 6,302,596 Specifications (Column 7, Line 40 to 52)